System, combination and method for controlling airflow in convective treatment

ABSTRACT

In a convective system that includes a blower to thermally treat and pressurize air, a convective device to receive and convect the thermally-treated pressurized air, and an air hose to conduct a flow of thermally-treated pressurized air from the blower to an inlet port in the convective device, an interface device is provided to control the flow of air at the interface where the inlet port and an end of the air hose operate to conduct the flow of air out of the air hose into the convective device. The interface device is received at the end of the air hose and operates to support the flow of air out of the end when the end and the inlet port are brought together. The interface device operates to stop, inhibit, or restrict the flow of air out of the end when the end and the inlet port are separated.

PRIORITY AND RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 10/131,068,which is a continuation-in-part of U.S. patent application Ser. No.10/024,387, filed Dec. 17, 2001, now U.S. Pat. No. 7,220,273, which isincorporated herein by this reference.

U.S. patent application Ser. No. 10/024,387 claims priority as adivisional of U.S. patent application Ser. No. 09/546,078, now U.S. Pat.No. 6,447,538.

This application contains subject matter related to the subject matterof U.S. patent application Ser. No. 09/138,774 filed Aug. 24, 1998, nowU.S. Pat. No. 6,126,681, and to its continuation-in-part, U.S. patentapplication Ser. No. 09/546,078, filed Apr. 10, 2000, now U.S. Pat. No.6,477,538. Both of these patent documents are incorporated herein bythis reference.

FIELD OF THE INVENTION

This invention relates generally to forced-air convection treatment ofpersons and, more particularly, to a system, a combination, and a methodfor controlling airflow in convective treatment in order to preventinjury to a person such as might occur when thermally-conditioned(heated or cooled) air is discharged directly onto the person.

BACKGROUND OF THE INVENTION

A convective treatment system consists of a temperature-control/blowerunit (known simply as a “blower”), a ducting system, a convective devicesuch as a convective warming blanket, and/or an infusate heat exchanger.A blower aspirates air from an ambient environment, changes itstemperature to a desired value, pressurizes the air above the ambientpressure, and discharges the air at an exhaust port. U.S. Pat. No.6,126,393 describes such a blower and associated temperature and noisecontrol schemes. In an exemplary convective treatment system,pressurized, thermally regulated air produced by a blower is conveyedthrough a ducting system and delivered to a convective device, such as aconvective warming blanket, that distributes the thermally regulated airaround a person or a specific body area of a person. A person can be ahuman being, animal, or thing. In some applications, a blower unit maybe used to operate other accessory devices with or without a convectivedevice. In these stand-alone applications, the blower unit may be usedto warm infusates, such as blood or saline, through the use of a heatexchanger adapted to fit within the duct system. U.S. Pat. No. 5,807,332describes one type of nonconvective device that is used to warminfusates for administration into persons. The use of an infusate warmerdoes not preclude the concomitant use of a convective device; however,the distal end of the air supply duct is covered with an air diffuserduring the exclusive use of an infusate warmer. The user mustintentionally place the diffuser over the distal end of the air supplyduct. The diffuser allows the heated air to escape from the distal endof the air supply duct but prevents the heated air from striking thepatient directly.

A convective device may be embodied, for example, in an inflatabledevice which inflates with pressurized, thermally regulated air and hasone or more surfaces adapted for expelling air onto a person. Suchdevices may lie on, around, or under the person. A convective device isgenerally realized as a blanket, but can be embodied by other appliancesor attachments that are designed to be operated by or with theapplication of pressurized, thermally conditioned air. When used herein,the term “convective device” is intended to include all blankets, pads,covers, manifolds, and equivalent structures that operate as justdescribed. Irrespective of orientation, a convective device utilized forconvective thermal treatment of persons performs at least three basicfunctions. These functions are 1) the conveyance of thermallyconditioned air from at least one inlet port into the device, 2) theimposition of a heat gain or loss that changes the temperature of thethermally conditioned air, and 3) the extravasation of the thermallyconditioned air from the device. In the following discussion, theassumption is that such a convective treatment device is operated towarm a person by delivery of heat to the person.

In those convective treatment systems which warm a person by theapplication of heat, heat may be transferred by convection, radiation,and conduction, but convection generally predominates at the interfacebetween the convective device and the person. The rate of convectiveheat transfer depends on material properties, surface boundaryconditions, and significantly, fluid velocity.

Heat is lost from a convective treatment system whenever a temperaturegradient exists between it and the ambient environment. During normaloperation of the system, the temperature of the air expelled onto theperson is maintained at a level that is generally higher than theperson's skin surface temperature, but not high enough to cause tissuedamage. In order to counter the loss of heat from the system, however,the air is heated initially to a temperature that may exceed the thermaldamage threshold at the target site on the person's skin. Within certainlimits, the amount of heat lost from the system is predictable. Thispredictability allows the system to operate safely by measuring andcontrolling the temperature at the proximal end of the air supply ductthat connects the blower to the convective device. If any factors uponwhich the assumption of predictability depends are altered, however, thefluid temperature at the distal end of the duct system may be affected.

Several intrinsic and extrinsic factors contribute to the rate of heatloss from a convective treatment system. Among the intrinsic factors arethe surface area and material characteristics of the duct and convectivedevice, and the residence time of the warmed air within the duct andconvective device. Extrinsic factors include, but are not limited to,ambient temperature and air velocity in the area immediately adjacent tothe duct and the convective device. The residence time of the heatedfluid within the system is a function of its pressure and the resistanceexerted by the entire system. Factors that influence resistance are theduct diameter and length, the orientation of the duct, and theresistance of the convective device or devices.

One hazard associated with the use of convective treatment is burns.First-, second-, and third-degree burns have occurred through theimproper use of convective treatment systems. The burn hazard isaccentuated by the intentional or accidental alteration of the intrinsicor extrinsic factors that moderate the heat loss in the system. Thealteration of any of these factors introduces an unpredictable amount ofheat loss into the system, which can significantly alter the temperatureor velocity of the heated air delivered to the person. One of the moreimportant factors that influence the temperature of warm air flowing outof the air supply duct through the end where it connects to theconvective device is the residence time of the air within the duct. Theend through which air flows out of the air supply duct is usuallyreferred to as the “distal end” of the air supply duct. Typically, anozzle may be mounted to this end. The temperature of pressurized warmair exiting the duct at this end is called “nozzle temperature” (whetheror not a nozzle is mounted thereto). In general, a decrease in residencetime of the pressurized warmed air is usually associated with anincrease in the nozzle temperature of the air.

In the field, a common misuse of one or more components of a convectivetreatment system occurs. Either intentionally or accidentally, someusers fail to connect the convective device to the distal end of theduct and allow the heated air discharged from the distal end to makedirect contact with the person. In view of the fact that an air supplyduct is typically embodied as an air hose, this practice has come to beknown as “hosing” or “free-hosing.” In other cases, operators havefailed to connect the convective device to the duct and allowed theheated duct to make direct contact with the person's skin. Users whohave experienced therapeutic misadventures through this type of misusehave reported their experiences of thermal injuries to the FDA and themanufacturers of the offending convective treatment systems. Somemanufacturers of have responded by warning and training users andaffixing labels to the thermal-control/blower units and convectivedevices. Despite warnings, training, and labeling, however, personscontinue to be injured through misuse of warming devices.

The American Society for Testing and Materials (ASTM) has recentlycirculated a draft standard (ASTM F29.19.01) from the Subcommittee forPatient Warming Equipment entitled Standard Specification forCirculating Liquid and Forced Air Patient Temperature ManagementDevices. The members of the ASTM subcommittee recognized the hazardsassociated with the practice of free-hosing and developed requirementsfor equipment to limit skin surface temperatures to 48° C., or less,during any operating or fault condition. Additionally, the standardrequires the manufacturers of thermal-control/blower units to affix acautionary statement to the distal end of the air supply duct that warnsthe user against the practice of “free-hosing.” Thus, the ASTM standardexplicitly recognizes the importance of air temperature, and tacitlyacknowledges the role of airflow, in causing thermal burns.

Hosing causes at least four uniquely hazardous conditions to exist: 1)The loss of the resistance from the lack of an convective device leadsto a decrease in the residence time of warmed air in the air supplyduct. As the warmed air has less time to cool in the air supply duct, itarrives at the distal end of the duct at a higher than normaltemperature; 2) The lack of airflow resistance from the absence of theconvective device also leads to an increase in the air velocity that isexhausted from the supply duct; The relative increase in air velocitycan lead to significantly higher heat transfer rates if the air strikesthe skin; 3) The lack of an convective device makes it possible for thehigh temperature and high velocity air to strike directly the person'sskin over a very small area. In essence, all, or most, of the heatenergy intended to be distributed over a large surface area isconcentrated onto a very small area; and 4) The lack of an convectivedevice makes it possible for the air supply duct itself to make directcontact with the person's skin.

It is manifest that the hazards of hosing are not intentionally visitedon any victim. Nevertheless, it is the case that large caseloads andnear-crisis conditions can distract the attention of those who are incharge of the immediate operation of convective treatment systems. Insuch circumstances, the practitioner may be unaware of the developmentof conditions that pose a hazard of burns, or may be forgetful of knownconditions that require close and constant attention. Accordingly,significant benefits would be realized by safety provisions that operateautomatically to reduce the risk of harm that can arise during theoperation of convective treatment systems. Especially desirable aremeasures that would automatically mitigate the potential of burns thatmight occur when the air supply duct is separated from the convectivedevice in a convective treatment system that delivers warmed air fortreatment.

The assignee of this application has designed safety provisions thatreduce the risk of burns by modulating the operation of a blower inresponse to changes in the integrity of the connection between the airduct and the convective device. These provisions are set out in U.S.Pat. No. 6,126,681 and a continuation-in-part thereof, U.S. patentapplication Ser. No. 09/546,078, both of which are incorporated hereinby this reference. However, these provisions must be implemented in thestructure and operation of a blower, and implicate redesign andreconstruction of exiting blower architecture.

Accordingly, there is an immediate need for additional,easily-implemented measures in convective treatment technology to 1)automatically mitigate a potentially unsafe condition irrespective of anoperator's awareness of the unsafe condition, 2) prevent the intentionalor unintentional misuse of convective treatment system components byusers who fail to connect the appropriate convective devices to thedistal end of the air supply duct and thereby allow heated air to makedirect contact to the person, and 3) prevent the air supply duct fromcausing thermal injury to the person if it makes direct contact with theperson's skin.

SUMMARY OF INVENTION

It is an object of this invention to automatically correct the conditionwhere an air supply duct that is still conducting pressurized air is notconnected to a convective device.

A further object of this invention is to correct the condition in a waythat does not interfere with the normal operation of a convective deviceor an accessory device whenever these devices are properly attached tothe air supply duct.

The invention is based on the critical realization that the there existsan interface in a convective treatment system where measures can beimplemented to reduce, if not stop, the flow of heated air when the airsupply duct is disconnected, uncoupled, or detached from the convectivedevice. The interface is where the connection, coupling, or attachmentof the air supply duct with the convective device is made. At thisinterface, an interface device is provided that reduces, restricts orstops the flow of air through the end when the end is disconnected,uncoupled, or detached from the convective device. The interface devicemay be manually operated or self-actuating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate a convective treatment system in which theinvention is deployed. FIG. 1B is a magnified partial perspective viewof a portion of a convective device where an inlet port is located, withan end of an airhose positioned to e received in the inlet port.

FIGS. 2A-2E illustrate an embodiment of an interface device according tothe invention.

FIGS. 3A-3E illustrate another embodiment of an interface deviceaccording to the invention.

FIGS. 4A and 4B illustrate another embodiment of an interface deviceaccording to the invention.

FIGS. 5A-5C illustrate another embodiment of an interface deviceaccording to the invention.

FIGS. 6A and 6B illustrate another embodiment of an interface deviceaccording to the invention.

FIGS. 7A and 7B illustrate another embodiment of an interface deviceaccording to the invention.

FIGS. 8A-8C illustrate another construction of the embodiment of FIGS.7A and 7B.

FIGS. 9A and 9B illustrate another construction of the embodiment ofFIGS. 7A and 7B.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In this description, a convective warming system will be described,together with certain elements of such a system. The elements will bedenominated by terms that are selected for syntactic convenience andutility in suggesting a structure or a function. The terms are notselected, nor are they intended, to constrain or limit the range ofstructural and functional equivalents to which the elements, alone or incombination, are entitled.

In this regard, the terms “blower” and “convective device” are definedabove. The term “air supply duct” is used in the background to denote atubular passage through which air is pressurized by the blower andconducted from the blower to a convective device in a convectivetreatment system. Hereinafter, the term “air hose” will be used in placeof “air supply duct” in order to convey the sense of a flexible tubularpassage. The air hose has two ends, one for connection to the blower,the other for connection to the convective device. For convenience ofthis description, and for no other purpose, the end that is to beconnected to the convective device may also be called a “distal” end. Inthe context of the invention, it is presumed that the air hose conductspressurized air that is warmed; indeed the air may even be called “hot”.This is intended to convey the sense that the temperature of the air hasthe potential to be raised to a level in a range, and that that level orany other level in the range results in a nozzle temperature that posesa risk of harm to a person if blown directly onto the person from thenozzle of the air hose, with the convective device removed.

The term “interface device” is also used in this description. In thisapplication, an interface device is a device, an apparatus, anappliance, or any equivalent structure or means, that wholly or partlycloses the distal end of an air hose in order to reduce, restrict,attenuate, or even stop the flow of air out of the air hose. One mayalso call an interface device a “flow-restricting” member or a“closure”, or a “stricture”, or any other equivalent term withoutnarrowing or surrendering the full range of equivalents that the term“interface device” is entitled to. As will become apparent the interfacedevice can perform these functions without a nozzle being mounted to theend. Further, the interface device may be received on a nozzle at theend, integrated into the structure of a nozzle at the end, or may itselfact also as a nozzle at the end.

The term “inlet port” is used in this description as well. Convectivedevices employ a variety of inlet port structures. In this application,an inlet port is any component of a convective device configured toallow for the ingress of pressurized air. Inlet ports may come in theform of sleeves, sheets flexible of material, and rigid material withdefined openings.

Refer to FIGS. 1A and 1B in which a convective treatment system 10 isillustrated. The elements of the system 10 include a blower 12 thataspirates air from the ambient environment, raises its temperature to adesired level, pressurizes the air above ambient pressure, anddischarges the heated, pressurized air at an exhaust port 14. An airhose 16, with two ends, 18 and 20, is provided. The end 18 is connectedto the exhaust port 14 and the air hose 16 conducts the heated,pressurized air to the end 20. The end 20 is connected, coupled, orjoined to the inlet port 22 of a convective device 24. In this regard,the equivalent action from the point of view of the convective device 24is that the end 20 is received in, or by, or near the inlet port 22.When the end 20 and the inlet port 22 are thus brought together, theheated, pressurized air is conducted through or out of the end 20 intothe convective device 24.

A representative convective device with an inlet port is described indetail in the assignee's U.S. Pat. No. 6,309,408, which is incorporatedby this reference. The convective device 24 and its associated inletport 22 may be understood with reference to the '408 patent, in which aninflatable device has an opening around which is mounted a relativelystiff sheet of cardboard material. The sheet of cardboard material hasan opening that is aligned with the opening in the inflatable device.The sheet provides structure to receive, retain and support the end ornozzle of an air hose in an inlet port. This arrangement, shown in FIGS.15 and 16 of the '408 patent, is instructive in understanding theembodiments which are described below.

Completing the description of the system 10, with reference to the '408patent as an instructive example, heated, pressurized air is conductedinto the convective device 24 which conveys the air from the inlet port22 into its interior, imposing a heat loss that reduces the temperaturelevel of the air, and extravises the heated, pressurized air through oneor more surfaces of the convective device 24. The system 10 thusdelivers thermally-regulated air to the convective device 24, and thedevice distributes the thermally-regulated air around a person or aspecific body area of the person.

In order to afford protection from injury that could result should theend 20 become separated from the inlet port 22, either by accident or byintentional action, an interface device that controls the interfacebetween the inlet port 22 and the end 20 is provided. The interfacedevice acts to wholly or partly close the end 20 of the air hose 16 inorder to reduce, restrict, attenuate, or even stop the flow of airthrough the end 20. When the end 20 is connected, coupled, or joined tothe inlet port 22, the interface device operates to allow pressurized,thermally-regulated air to flow easily through the end 20 into theconvective device 24. Following connection, when the end 20 isdisconnected, uncoupled, or separated from the inlet port 22, theinterface device operates to wholly or partly close the end 20 in orderto reduce, restrict, attenuate, or even stop the flow of air through theend 20. Refer now to the remaining drawings, which illustrate variousembodiments of the interface device.

Embodiment of FIGS. 2A-2E

In FIGS. 2A-2E an interface device that exemplifies this invention isillustrated. The interface device 200 includes two frusto-conicalsections 210 and 212 made of any material that can be joined to an endof an air hose and received in and supported by an inlet port such asthe inlet port 22. In this regard, taking the air hose 16 as an example,its end 20 may include an annulus 20 a made of a material that is easilyjoined to the material of which the sections 210 and 212 are made.Representative materials for the elements 210, 212, and 20 a mayinclude, for example, durable plastics, composites, or any equivalentmaterials or combinations thereof. The frusto-conical section 210 has awall 220 through which at least one opening is provided. For example,two opposing openings 221 and 222 are shown in these figures. Theopposing openings 221, 222 are elongate, semi-rectangular fenestrationswhich open through the wall 220. In this example, each of the openings221, 222 has a major dimension I which extends lengthwise on the section210. A single opening 225, also an elongate semi-rectangularfenestration, opens through the wall 220. This opening 225 has a majordimension I which extends crosswise on the section 210. The narrow end228 of the section 210 has a structural member 229 that extends entirelyacross it. The member 229 is illustrated as having the shape of an hourglass with rounded ends, although this is not necessary to the practiceof the invention. The wide end 230 of the frusto-conical section 210 isopen. The frusto conical section 212 acts on or against thefrusto-conical section 210 in order to provide relative rotationtherewith. In the example shown in these figures, this is accomplishedby disposing the section 212 on the inside of the section 210 with itsnarrow end 248 brought near to or against the inside surface of thenarrow end 228 of the section 210 and fixing, joining, or attaching thesection 210 to the annulus 20 a near the wide end 230 of the section210. This allows the section 212 to rotate about its axis, at the end20, within the frusto-conical section 210. In this arrangement, thesection 212 has a wall 240 through which at least one opening isprovided. For example, two opposing openings 241 and 242 are shown inthese figures. The opposing openings 241, 242 are elongate,semi-rectangular fenestrations which open through the wall 240. In thisexample, each of the openings 241, 242 has a major dimension I whichextends lengthwise on the section 212. The narrow end 248 of the section212 has a structural member 249 that extends entirely across it. Themember 249 is illustrated as having the same shape as the member 229,although this is not necessary to the practice of the invention. Thewide end 250 of the frusto-conical section 212 is open. Each of thesections 210 and 212 is provided with a semi-cylindrical trunnion, withthe trunnion 252 being mounted on and projecting outwardly from the wall220 at the end 229 a of the opening 220, and the trunnion 254 beingmounted on and projecting outwardly from the wall 240.

As shown in the figures, especially FIGS. 2A and 2D, the section 212 isreceived in the section 210, and the wide end 230 of the section 210 isreceived in and joined to the annulus 20 a. The joinder of theseelements may be by any appropriate means that substantially or entirelyseals the joint between the annulus 20 a and the section 210. The jointmay be permanent or reducible; it may be immobile or permit rotationbetween the interface device 200 and the annulus 20 a. When the section212 is received in the section 210, the trunnion 254 extends through theopening 225 in the section 210, constraining the rotation of the section212 within the section 210 to an arc whose length extends from the end229 a to the end 229 b of the opening 225. In these figures, the arc isapproximately 90°. When the section 212 is rotated in the direction ofarrow 284 toward the end 229 a, rotation is stopped at a position of thesection 212 where its opposing openings 241, 242 are respectivelyaligned with the opposing openings 221, 222 of the section 210. At thisposition, seen best in FIG. 2D, the alignment of the opposing openingsprovides at least one aperture through the interface device 200 that isin communication with the end 20 and permits air to flow through the airhose 16, to and through the end 20, through the interface device 200, ata relatively high rate. In this figure (and in FIGS. 2C and 2E), airflow is indicated by arrows 283. For example, the rate may be in anoperational range from 24 CFM (cubic feet per minute) to 40 CFM. Next,when the section 212 is rotated toward the end 229 b, rotation isstopped at a position of the section 212 where its opposing openings241, 242 are respectively blocked, closed, or shut by the unaperturedportion of the wall 220. Similarly, at this position of the section 212,the opposing openings 221, 222 of the section 210 are respectivelyblocked, closed, or shut by the unapertured portion of the wall 240. Atthis position, the blocking of the openings 221,222,241, and 242, andclosure of at least the narrow end 228 of the section 210 reduces,attenuates, restricts or blocks air flowing through the end 20 and theinterface device 200. The effect produced thereby can range from whollycutting off the airflow through the end 20 and the interface device 200to restricting the airflow therethrough to some rate that is lower thanthe lower end of the operational range.

As thus far described, the interface device 200 can be operatedmanually. Self-actuated operation of the interface device 200 can beunderstood with reference to FIGS. 2 A and 2B. In these figures a spring270 has a coil 271 and two ends 272 and 274. The end 272 is disposed atone end of the spring coil 271, crosswise to the axis of the coil. Theend 274 projects from the other end of the spring coil 271 generallyparallel to the axis of the coil. A flange 276 projecting into thefrusto-conical section 210 from the structural member 229 has a slot 277that receives the end 272 of the spring 270. A thick annulus 278 ismounted on the rear surface of the structural member 249 of thefrusto-conical section 212. A recess 279 is centered in the structuralmember 249 and the thick annulus 278, and a hole 280 is provided throughthe member 249 and the annulus 278. The spring 270 is seated in therecess 279 and the end 274 of the spring 270 extends through the hole280 when the section 212 is received within the section 210. Whenseated, the spring 270 acts between the frusto-conical sections 210 and212 by urging the section 212 to rotate in the direction of the arrow282 until the trunnion 254 engages the end 229 b of the opening 225.This stops the frusto-conical section 212 at the position where the flowof air is reduced, attenuated, restricted or blocked. Manual engagementof the trunnion 254 with a force directed in the direction of the arrow284 moves the trunnion to the end 229 a where it abuts the trunnion 252and rotates the frusto-conical section 212 to the position where thealignment of the opposing openings provides at least one aperturethrough the interface device 200 that is in communication with the end20 and permits air to flow from the end 20, through the interface device200, at the relatively high rate.

The operation of the interface device with respect to the interfacebetween the end 20 of the air hose 16 and the inlet port can beunderstood with reference to FIGS. 2C-2E. Assuming for illustration thatthe inlet port 22 includes an inlet port structure such as thatdisclosed in U.S. Pat. No. 6,309,408, it would include a sheet 290 offlexible, somewhat deformable material (such as cardboard) in which aport opening 291 is provided. The sheet 290 may also include a tab 292with an opening 294. The interface device 200 is mounted to the end 20of the air hose 16 as described above, and the interface device 200 ismated with the port opening 291, with the narrow ends 228 and 248oriented toward and extending through the port opening 291. Eitherbefore or after the narrow end of the interface device 200 is placed inthe port opening 291, the frusto-conical section 212 is rotated in thedirection of the arrow 284 until the trunnion 254 is brought against thetrunnion 252. This places the section 212 into the position where thealignment of the opposing openings provides at least one aperturethrough the interface device 200 that is in communication with the end20 and permits air to flow from the end 20, through the interface device200, at the relatively high rate. The frusto-conical section 212 can beretained in this position in resistance to the urging of the spring 270by means of the opening 294 which is brought over the trunnions 252 and254 by bending the tab 292 toward the interface device 200. Now, if theair hose 16 is disconnected from the inlet port, the tab 292 is bentaway from the trunnions 252 and 254, and the spring 270 will urge thefrusto-conical section in the direction of the arrow 282 to the positionat which the flow of air out of the end 20 is reduced, attenuated,restricted or blocked.

Embodiment of FIGS. 3A-3E

Refer now to FIGS. 3A-3E for an understanding of another embodiment ofthe interface device. In these figures, the interface device embodimentincludes a shutter. In this embodiment, when the end 20 and the inletport 22 are brought together the shutter opens (or, is opened) to permitpressurized air to flow out of the end 20 into the convective device.Likewise, when the end 20 is separated from the inlet port 22 theshutter closes (or, is closed), to reduce, restrict, or prevent the flowof air out of the end 20, thereby preventing burn accidents or improperoperation of the equipment.

The interface device 300 includes an end piece 305 comprising a tubularsection 307 and a front piece 309 in the form of a concaved rectangularframe. The front piece 309, disposed on one end of the tubular section307, has a concaved rectangular surface 311 around the periphery ofwhich a frame with side slots (one indicated by 313) is disposed. Agenerally triangular opening 315 is disposed generally in the center ofthe surface 311 and there is a rounded half cylindrical slot 317disposed on one edge of the opening 315 generally on the longitudinalaxis of the surface 311. The end piece 305 is preferably a unitaryelement formed, possibly, by molding a durable plastic. The end piece305 is assembled to an annular collar 320 on the end 20, for example bythreaded screws that extend through the second end of the tubularsection 307, although other joinings are possible. When assembled inthis manner, the opening 315 permits pressurized air to flow out of theend 20.

The interface device 300 further includes a flexible shutter 325 havinga generally rectangular shape that corresponds to the rectangular shapeof the surface 311. The flexibility of the shutter 325 permits it toassume the concaved shape of the surface 311 when the shutter isreceived in the frame of the front piece 309 with its sides 326 receivedin the side slots 313. Alternatively, the shutter 325 could be formed ofa hard plastic conformed to fit the shape of the surface 311. Theshutter 325 is shorter than the surface 311, enabling it to slidethereon. The shutter includes, in one end portion, one or moretriangular openings 327. When the shutter is slid away from the opening315 in the surface 311 to a position against the edge 318 of the endpiece, the unbroken portion of its other end portion blocks the opening315, thereby preventing or restricting the flow of pressurized air outof the end 20. When the shutter 325 is slid toward the opening 315 to aposition against the edge 319, the one or more openings 327 align withthe opening 315 and permit pressurized air to flow out of the end 20.

The operation of the shutter 325 may be manual or it may be automated byprovision of a spring 330. The spring 330 acts between the shutter 325and the end piece 305, being relatively more compressed when the shutter325 is slid toward the edge 319, and urging the shutter from thatposition toward the edge 318. The spring 330 is retained to act in thismanner by a gudgeon 328 that projects off one side of the shutter 325into one end of the spring, in the direction of the cylindrical slot317, which receives the other end of the spring 330. A retainer 331extends away from the other side of the shutter 325 and broadens into atab 333. The shutter 325 is retained against the surface 311, in theframe of the front piece 309 by a concaved rectangular cover 340 havinga center opening 341 aligned with the opening 315. An elongate slot 343opens into the periphery of the center opening 341, and an arcuate lip342 is provided adjacent the periphery of the center opening 291,diametrically opposite the slot 343. The retainer 331 projects throughthe slot 343 and traverses the slot from end to end as the shutter 325is moved between the positions described above. When the shutter 325 isslid to the position at which it is stopped against the edge 319, theopenings 315, 327, and 341 align, permitting pressurized air to flow outof the end 20. At this position, the retainer 331 is retained againstthe arcuate lip 345.

A self-actuating operation of the interface device 300 is best seen inFIGS. 3D and 3E. To bring the end 20 together with the inlet port 22,the shutter 325 is slid toward the edge 319 by pressure applied againstthe tab 333. With the shutter 325 held in this position, the end piece305 is brought against the sheet 290 of the inlet port 22, with the tab333 extending through the port opening 291. The compressed spring 330urges the retainer 331 into engagement against the periphery of the portopening 291. This keeps the shutter in the position at which pressurizedair flows out of the end 20, through the inlet port 22. The end 20 isseparated from the inlet port 22 by sliding the end piece against thesheet 290 in the direction of the arrow 370. This disengages the tab 333and allows the shutter to be returned by the spring 330 to the positionagainst the 318 where the opening 309 is blocked, covered, or closed bythe unaperatured portion of the shutter 325.

Embodiment of FIGS. 4A and 4B

Refer now to FIGS. 4A and 4B for an understanding of another embodimentof the interface device. In these figures, the interface deviceembodiment 400 includes a sleeve 418 of flexible material having an openend 422 that transitions to a shallow bowl-like collar and an end 424that has a normally closed configuration in which opposing sections ofthe sleeve 418 at the end 424 abut without being permanently joined. Thesleeve 418 is made of a durable flexible plastic such as polypropyleneor polyethylene and has a remembered shape that maintains the end 424 inits normally closed configuration. Opposing longitudinal living hinges415 and 417 connect two opposing segments 419 and 420 of the sleeve 418.Forces applied in opposition to the living hinges 415 and 417 near theend 424 (indicated by arrows 435) cause the end 424 to open and thesleeve 418 to assume an open tubular configuration. When the opposingforces 435 are released, the sleeve 418 returns to its remembered shapein which the end 424 is in its normally closed configuration.

The interface device 400 is operated by applying opposing forces to eachside of the sleeve 418, on the living hinges 415 and 417, near the end424 as indicated by the arrows 435 in FIG. 4B. This opens the end 424into a roughly cylindrical shape that is received in the port opening291. The end 424 is inserted into the port opening 291, and the opposingforces are released. This causes the sleeve to seek its rememberedshape, and engage the rim of the port opening 291, thereby retaining thenow-open end 424 within the port opening 291, permitting air to flowfrom the end 20, through the interface device 400, at the relativelyhigh rate. To withdraw the interface device 400 from an inlet port,opposing forces are again applied to the sleeve 418 to flex the sides ofthe sleeve 418 at the living hinges 415, 417 in the directions indicatedby the arrows 435, thereby disengaging the sleeve 418 from the portopening 291 and allowing the end 424 to be withdrawn from the portopening 291. When the end 424 is withdrawn from the inlet port and theopposing forces 435 are released, the sleeve 418 returns to itsremembered shape, thereby returning the end 424 to its normally-closedconfiguration, in which the flow of air out of the end 20 is reduced,attenuated, restricted or blocked.

Embodiment of FIGS. 5A-5C

Refer now to FIGS. 5A-5C for an understanding of another embodiment ofthe interface device. In these figures, the interface device embodiment500 includes a spring structure with a base ring 510 having an opening511. An imaginary axis A, centered in and perpendicular to the base ring510, may be defined. A pair of elongate flexible tines 512 and 514 aremounted in opposition on one surface of the base ring 510, extendingalong and beside the axis A. The other surface of the base ring 510 hasthe same shape and dimensions as the annulus 20 a. The flexible tines512 have the shapes of shallow descending arcs that open in oppositedirections away from the axis A. The flexible tines 512 and 514 areformed from any appropriate flexible material that retains a memory ofits original shape when flexed by an applied force and that returns tothe remembered shape when the force is removed. One such material is asturdy, durable plastic such as polypropylene or polyethylene. Theflexible tines 512 and 514 have wedge-shaped tips with vertices 513 and515, respectively, that extend outwardly from the tines. A sleeve 518 ofdurable flexible material such as polypropylene or polyethylene ismolded into a shape having opposing ends 522 and 524, wherein the end522 transitions to a shallow bowl-like collar and the end 524 has anormally closed configuration in which opposing sections of the sleeveat the end 524 abut without being permanently joined. Force applied inopposition to the sides of the end 524 cause the end 524 to open.Opposing apertures 519 and 520 are provided through the sleeve 518 nearthe end 524. The interface device 500 is assembled by attaching,joining, or bonding the base ring 510 concentrically to the annulus 20 aand then sliding the sleeve 518, end 522 first, over the tines 512 and514, until the end 522 is brought against the base ring 510. When theend 522 is seated against the base ring 510, the vertices 513 and 515are received in and protrude through the apertures 520 and 519. The end522 is attached, joined, or bonded to the base ring 510. When assembled,the interface device is maintained in a normally closed configuration bythe tines 512 and 514 which seek their remembered shapes, exertingdrooping outwardly-directed opposing forces on the end 524, whichmaintains the end 524 in its normally-closed configuration. As best seenin FIGS. 5B and 5C, the drooping component of the curvature of tines 512and 514 imposes a pronounced hook on the portion of the sleeve 518 thatincludes the end 524. The interface device 500 is operated by applyingopposing forces to each side of the sleeve 518, near the end 524 justbehind the vertices 513 and 515, as indicated by the arrows 535 in FIG.5B. This opens the end 524 into a roughly cylindrical shape that isreceived in the port opening 291. The end 524 is inserted far enoughinto the port opening 291 to place the vertices 513 and 514 through theport opening 291 where they engage the back surface of the sheet 290.When the opposing forces are removed, the tines 512 and 514 seek theirremembered shapes and retain the now-open end 524 within the portopening 291, permitting air to flow from the end 20, through theinterface device 500, at the relatively high rate. To withdraw theinterface device 500 from an inlet port, opposing forces are againapplied to the sleeve 518 to flex the sides of the sleeve 518 and thetines 512 and 514 in the directions indicated by the arrows 535, therebydisengaging the vertices 513 and 514 from the sheet 290. When the end524 is withdrawn from the inlet port and the opposing forces 535 arereleased, the tines 512 and 514 seek their remembered shapes, therebyreturning the end 524 to its normally-closed configuration, in which theflow of air out of the end 20 is reduced, attenuated, restricted orblocked.

Embodiment of FIGS. 6A and 6B

Refer now to FIGS. 6A and 6B for an understanding of another embodimentof the interface device. In these figures, the interface deviceembodiment 600 includes a single frusto-conical section 610 made of adurable flexible material such as plastic and having a narrow end 628and a wide end 630. Both of the ends 628 and 630 are open, and the wideend 630 transitions to a shallow bowl-like collar. At the narrow end 628there are four elongate slots 612 that extend from the end 628longitudinally along the section 610 for about a third of the length ofthe section 610. The slots are arrayed at 90° around the narrow end 628of the section 610 and define four corresponding legs 614 extending fromthe narrow end 628. The legs 614 are flexible and can be flexed inwardlytoward one another. A ball or sphere 620 of light durable material suchas plastic is disposed on the inside of the section 610, wherein it isfree to move between the narrow end 628 and the wide end 630. The ball620 has a diameter that fills the narrow end 628. The ball 620 may behollow and have apertures therein to allow a limited amount of air topass through the ball itself. Although not shown in these drawings, theball 620 may be tethered to the inside of the section 610, orconstrained therein by a cross piece at the wide end 630. The interfacedevice 600 is assembled by receiving the annulus 20 a in the shallowbowl-like collar at the wide end 630 where it is attached, joined, orbonded to the collar.

The interface device 600 is operated by squeezing together the legs 614.The narrow end 628 is inserted into the port opening 291, which, forthis embodiment may have a quatrefoil pattern for receiving the legs614. When the squeezing force is removed from the legs, they spring backtoward their unflexed positions and frictionally engage the port opening291. Alternatively, the engagement of the port opening 291 may beeffected by relying on the taper of the legs 614. In this case as theinterface device 600 engages sheet 290, the wide end of the tapered leg614 results in a friction fit with the opening 291 The quatrefoilpattern of the port opening prevents ball 620 from entering the narrowend 628, permitting air to flow from the end 20, through the interfacedevice 600, at the relatively high rate. To withdraw the interfacedevice 600 from an inlet port, the legs 614 are again squeezed togetheruntil they are disengaged from the port opening 291. When the narrow end628 is withdrawn from the inlet port and the squeezing force isreleased, the legs 614 seek their remembered positions, and the ball 620is now free to enter the narrow end 620, where it is impelled by thepressurized air flowing through the end 20. Here, the ball 620 inreduces, attenuates, restricts or blocks the flow of air out of the end20.

Embodiments of FIGS. 7A/7B, 8A-8B, and 9A/9B

FIGS. 7A, 7B, 8A-8C, 9A and 9B contain subject matter originallydisclosed in FIGS. 14A, 14B, 15A-15C, 16A, and 16B, respectively, ofU.S. patent application Ser. No. 09/546,078 from which this applicationis continued, in part. In these figures another embodiment of theinterface device relies on the opening and closing of a valve to controlthe flow of air out of the end 20. In this embodiment, bringing the end20 and the inlet port 22 together causes the valve to open and permitspressurized air to flow out of the end 20 into the convective device.Likewise, separating the end 20 from the inlet port 22 causes the valveto close, reducing, restricting, or preventing the flow of air out ofthe end 20, thereby preventing burn accidents or improper operation ofthe equipment.

FIG. 7A depicts an inlet port 22, the end 20, and a nozzle 700 (shownpartially received in the end 20 for illustration only). The nozzle 700,received in the end 20 of the air hose 16, includes a valve 730. As seenin FIG. 7B, as the nozzle 700 is received in the inlet port 22, thevalve 730 including a flap 734 cooperates with the inlet port 22 toenable airflow out of the end 20 through the inlet port 22. Also, whileFIG. 7B depicts the valve flap 734 opening toward the inlet port 22 uponactivation, it is also possible to design a valve system in which theflap 734 opens towards the air hose 16 upon activation.

The nozzle 700, preferably made of a durable material such as a hardplastic or equivalent, has an arch-shaped forward section 706, thattransitions to a shoulder 708. The shoulder 708 transitions to a reararched-shaped section 709. The rear section 709 is enabled to fit snuglyto the end 20 of the air hose 16, by means of an adapter 20 b. Thenozzle 700 is assembled, attached, or brought together with the air hose16 by inserting the nozzle 700, rear section 709 first, into the adapter20 b so far as to bring the shoulder 708 against the adapter 20 b.There, the shoulder 708 may be bonded to one side of the adapter 20 b,the other side of which is bonded to the end 20 of the air hose 16.

The end 20 and the inlet port 22 are brought together by inserting thearched-shaped section 706 into the port opening 291 a (which has anarched shape that corresponds to that of the section 706) open endfirst, and sliding the section 706 into the opening 291 until theengagement between the valve 730 and the opening 291 cause the valve toopen, as is explained below.

The flap 734 has an arched shape with a dimension 736 substantially thesame as the corresponding inner dimension of the arch-shaped section709. It should be noted that the flap 734 need not perfectly seal theend 20 to be effective. The flap 734 stops, blocks, or restricts theflow of air, or substantially stops, blocks or restricts the flow ofair, when the end 20 is not received in the inlet port 22.

As depicted in FIGS. 7A and 7B, in addition to the flap 734, the valve730 includes a hinge lever 738 which is rigidly attached to the flap734. At the intersection of the hinge lever 738 and flap 734 is an axleor pin (not shown) about which the flap 734 and hinge lever 738 pivot.The hinge lever 738 cooperates with the inlet port 22, being moved froma position perpendicular to the air hose 16, to a position against theair hose 16, to permit the end 20 to be brought together with the inletport 22. The engagement of the hinge lever 738 with the lower edge 291 bof the opening 291 a rotates the flap 734 from a position blocking theflow of air (shown in FIG. 7A) to a position (open position) in whichair may flow when the end 20 is brought together with the inlet port 22.Not specifically shown is the mechanism which returns the flap 734 fromthe open position to the blocking position (FIG. 7A) when the end 20 isdisengaged from the inlet port 22. The return-mechanism can be a springor some such torsioning member (not shown) which is put under load bythe action of the flap 734 being forced into the open position (FIG.7B). Additionally, in some orientations, the flap 734 can be returned toits seated position by the frictional force of the airflow within theair hose 16. Once the valve flap 734 is seated, it will be held in placeby the static pressure developed by the blower.

Optionally, a pair of magnets 739 a and 739 b may be used to keep theflap 734 in the blocking position when the end 20 is separated from theinlet port 22. The first magnet 739 a, is disposed in the rear section709 and the second magnet 739 b is disposed the flap 734. The firstmagnet 739 a cooperates with the second magnet 739 b so that the flap734 blocks the flow of air when the end 20 is separated from the inletport 22. Although not specifically shown, magnets can also be used withthe flap 734 of the actuator mechanisms shown in FIG. 8A, describedbelow. In another aspect of this embodiment, not shown, the flap 734 maybe opened in the direction of the air hose 16 instead of the inlet port22, so that the flow of air through hose 16 acts to close the flap 734when it is not engaged.

FIGS. 8A through 8C depict a valve 830 with a circular valve flap 834,coupled to a cam actuation mechanism, and disposed in a single,substantially tubular section 806. The tubular section 806 is attached,at one end to the end 20 of the air hose 16. The flap 834 has a diametersubstantially equal to the diameter of the tubular section 806. As shownin FIG. 8A, the flap 834 includes a pair of cams 840 a and 840 b rigidlyattached to the flap 834, 180 degrees apart. Alternately, the cam can beattached to an axle running through the diameter of the flap 834, withthe axle being rigidly attached to the flap, so that the face of theflap and the cam facets remain in a fixed relationship. The camactuation mechanism includes rounded surfaces which permit the cams 840a/840 b, and attached flap 834, to rotate as the cam engages the surfacesurrounding the inlet port 22. The rotation of the cams 840 a/840 b isshown if FIG. 8B. As shown in FIG. 8C, the flat facet surfaces of thecams 840 a/840 b permit those surfaces to fixedly seat against the inletport 22 as the end 20 and the inlet port 22 are brought together. Withthe cams 840 a/840 b seated, the flap 834 is locked in an open positionto permit the flow of air. Not shown is a return mechanism which forcesthe flap 834 into the blocking position (FIG. 8A). As above, the returnmechanism can be a spring, or equivalent that is put under load as theflap 834 is forced into the open (non-blocking) position.

FIGS. 9A and 9B depict a gear rack valve actuator mechanism for a valve930 having a circular valve flap 934. The mechanism includes a lever 950which engages the inlet port 22 to open the flap 934. The lever 950 isconnected to a first gear 952, the teeth of which are intermeshed withthe teeth of a second gear 954. In turn, the second gear 954 is attachedto the flap 934. As the lever 950 is engaged, it is forced into the bodyof the hose 16. The action of the lever 950 and the gears 952/954 openthe flap 934 so that pressurized air can pass out of the end 20 intoinlet port 22. Optionally the a pair of magnets 739 a/739 b are used tokeep the flap 934 in the blocking position when the end 20 is separatedfrom the inlet port 22. Alternatively, the opening of the flap 934 intothe direction of the airflow acts to force the flap 934 into a blockingposition when lever 950 is not engaged by the inlet port 22.

1. A system for controlling airflow in convective treatment, comprising:a blower; an air hose with a first end receivable in the blower and asecond end; a convective device with an inlet port to receivepressurized air from the second end; and, an interface device mounted tothe second end and receivable by the inlet port, the interface deviceincluding a shutter slidably disposed near the second end and moveablebetween a first position where the shutter prevents the flow of air outof the second end and a second position where the shutter permits theflow of air out of the second end.
 2. The system of claim 1, wherein theinterface device acts between the inlet port and the second end to keepthe shutter in the first position when the interface device is receivedby the inlet port.
 3. The system of claim 1, the interface devicefurther including: a tubular end piece with two ends, a first end of thetubular end piece receivable on the second end of the air hose: a frontpiece disposed on the second end of the tubular piece; a surface on thefront piece, the surface having a periphery; a frame on the surface,with slots disposed around the periphery; and, an opening in thesurface; the shutter being retained in the slots so as to slide on thesurface, over the opening.
 4. The system of claim 3, wherein the frameis a concave rectangular frame, the surface is a concave rectangularsurface, and the shutter is a flexible shutter.
 5. The system of claim3, wherein the frame is a concave rectangular frame, the surface is aconcave rectangular surface, and the shutter has a shape that fits theshape of the concave rectangular surface.
 6. The system of claim 3, theinterface device further including a retainer disposed on the shutter toengage the inlet port so as to keep the shutter in the second position.7. The system of claim 3, the shutter including first and secondportions, the first portion being unbroken, and the second portionincluding at least one opening, such that when the shutter is in thefirst position, the first portion covers the opening in the surface, andwhen the shutter is in the second position, the at least one opening inthe shutter is aligned with the opening in the surface.
 8. The system ofclaim 7, the interface device further including: a slot in the surface,disposed generally on a longitudinal axis of the surface; a gudgeondisposed on the shutter to face the slot in the surface; and, a springacting between the slot in the surface and the gudgeon; the spring beingcompressed by the slot and the gudgeon when the shutter is in the secondposition.
 9. The system of claim 8, the interface device furtherincluding: a cover disposed on the frame such that the shutter issandwiched between the surface and the cover; an opening in the coveraligned with the opening in the surface; a slot in the cover extendingto the opening in the cover; a retainer disposed on the shutter to movein the slot in the cover as the shutter moves between the first andsecond positions.
 10. The system of claim 9, wherein the retainer ispositioned on the shutter to engage the inlet port, thereby to retainthe shutter in the second position, with the spring compressed.
 11. Thesystem of claim 10, wherein the shutter is returned to the firstposition by the compressed spring acting against the gudgeon when theretainer is released from the inlet port.
 12. The system of claim 10,wherein the shutter is returned to the first position by the compressedspring acting against the gudgeon when the interface device is removedfrom the inlet port.
 13. The system of claim 7, further including meansfor moving the shutter to the first position when the interface deviceis removed from the inlet port and for retaining the shutter in thesecond position when the interface device is received by the inlet port.14. An interface device for controlling airflow delivered by an air hoseto an inlet port of a convective thermal treatment apparatus,comprising: a tubular end piece with first and second ends, the firstend being receivable on the air hose; a front piece disposed on thesecond end and receivable in the inlet port; a surface on the frontpiece, the surface having a periphery; a frame on the surface, withslots disposed around the periphery; and, an opening in the surface; theshutter being retained in the slots so as to slide on the surface, overthe opening, between a first position where the shutter blocks theopening in the surface in response to the interface device being removedfrom the inlet port and a second position where the shutter opens theopening in the surface in response to the interface device beingreceived in the inlet port.
 15. The interface device of claim 14,wherein the frame is a concave rectangular frame, the surface is aconcave rectangular surface, and the shutter is a flexible shutter. 16.The interface device of claim 14, wherein the frame is a concaverectangular frame, the surface is a concave rectangular surface, and theshutter has a shape that fits the shape of the concave rectangularsurface.
 17. The interface device of claim 14, further including aretainer disposed on the shutter to engage the inlet port so as to keepthe shutter in the second position.
 18. The interface device of claim14, the shutter including first and second portions, the first portionbeing unbroken, and the second portion including at least one opening,such that when the shutter is in the first position, the first portioncovers the opening in the surface, and when the shutter is in the secondposition, the at least one opening in the shutter is aligned with theopening in the surface.
 19. The interface device of claim 18, furtherincluding: a slot in the surface, disposed generally on a longitudinalaxis of the surface; a gudgeon disposed on the shutter to face the slotin the surface; and, a spring acting between the slot in the surface andthe gudgeon; the spring being compressed by the slot and the gudgeonwhen the shutter is in the second position.
 20. The interface device ofclaim 19, further including: a cover disposed on the frame such that theshutter is sandwiched between the surface and the cover; an opening inthe cover aligned with the opening in the surface; a slot in the coverextending to the opening in the cover; a retainer disposed on theshutter to move in the slot in the cover as the shutter moves betweenthe first and second positions.
 21. The interface device of claim 20,wherein the retainer is positioned on the shutter to engage the inletport, thereby to cause the shutter to be retained in the second positionand the spring to be compressed.
 22. The interface device of claim 21,wherein the shutter is returned to the first position by the compressedspring acting against the gudgeon when the retainer is released from theinlet port.
 23. The interface device of claim 18, further includingmeans for moving the shutter to the first position when the interfacedevice is removed from the inlet port and for retaining the shutter inthe second position when the interface device is received by the inletport.
 24. A method for safely operating a convective thermal treatmentsystem, the method comprising: mounting an interface device with aslidable shutter to an air hose; mounting the interface device to aninlet port of a convective treatment device; in response to mounting theinterface device to the inlet port, sliding the shutter to an openposition permitting air flow from the air hose to the inlet port;providing a flow of heated air through the air hose to the inlet port;separating the interface device from the inlet port; and then, slidingthe shutter to a closed position preventing air flow out of the airhose.
 25. The method of claim 24, wherein sliding the shutter to theopen position includes compressing a spring in the interface device, andsliding the shutter to the closed position includes the compressedspring moving the shutter to the closed position in response toseparation of the interface device from the inlet port.